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Abstract

The Ganges had been the world's 8th largest river in terms of the volume of water discharge of 490 km3/yr to the ocean 4 prior to 1975. Since that time, over a period of two decades, India has reduced the Ganges discharge through Bangladesh to 40% from its original annual average discharge of 1,932+7-223 m3 /s by diverting water for irrigation in her upper states. The , resulting consequences have been disastrous due to the depletion of the surface water resources. One of the devastating consequences has been the generation of extreme climate. The summertime maximum temperature has risen to about 43.33°C . (110°F) from about 37.22°C (99°F). The heating degree days (HDDs) calculated with the base temperature of 30°C (86°F) show that the average value of HDD after the generation of extreme climate is 637C° (1146.6F 0 ) more than the value before the generation of the climatic extremity. During the era of the pre-diversion of water the relative humidity had to rise to 75% to generate heatstroke conditions at the then summertime maximum temperature of 37.22°C (99°F), whereas under the current summertime maximum temperature, the same conditions begin at a relative humidity value of45%. This results in prolonged exposure to heatstroke conditions for 40 million of the world's poorest people. Further, the wintertime minimum temperature has dropped from about 8.33°C (47°F) to about 4.44°C (40°F), and it still shows a dropping trend. This low temperature along with a wind speed of 16 to 24 km/hr creates hypothermal conditions, particularly for the oldest and the youngest persons and takes a heavy death toll. Cooling Degree Days (CDDs) calculated from a base temperature of 15°C (59°F) show that there are more fluctuations in CDDs in post-diversion time than in pre-diversion time. An estimation shows that at least 20 million trillion calories of heat are generated during the summertime in the Gangetic Bangladesh because of early drying of the surface water resources. Since water and the wet soil used to retain that heat due to the highest thermal capacity of water, there is a shortfall of the same amount of heat creating an environmental heat deficit during the wintertime in the absence of the surface water resources. To improve length and quality of life for the people of Biosphere III, the Farakka Barrage has to be demolished, and the original flow of the Ganges through itself and its distributaries in the delta must be restored. Introduction The Ganges basin in Bangladesh, hereafter called Biosphere III because of the unique ecodisastrous effects it has been suffering, has had an almost continuous shortage of water for more than two decades beginning in 1975. While Biosphere II is an artificially enclosed environment to simulate the living conditions is space, the term Biosphere III is introduced for this region marked with artificially created critical shortage of water and subsequent evolution of a series of situations like climatic extremes, fading tolerance of different species of living beings, arsenic poisoning of groundwater, epidemic form of environmental diseases, etc. In 1975, India started withdrawing the Ganges water by the operation of the Farakka Barrage, which is built over the Ganges about 18 km upstream from the Indo-Bangladesh common border. Although its stated purpose was to maintain navigability of the Calcutta Port located about 260 km downstream from the barrage poi

Recommended Citation

Adel, M. M.
(1999)
"Microlevel Climate Change due to Changes in Surface Features in the Ganges Delta,"
Journal of the Arkansas Academy of Science: Vol. 53
, Article 17.
Available at:
http://scholarworks.uark.edu/jaas/vol53/iss1/17